function(navigation_expression_parse)
    string(REPLACE "." ";" expression "${ARGN}")
    string(REPLACE "[" "<" expression "${expression}" )
    string(REPLACE "]" ">" expression "${expression}" )
    string(REGEX REPLACE "([<>][0-9:-]*[<>])" ";\\1" expression "${expression}")
    string(REGEX REPLACE "^;" "" expression "${expression}")
    return_ref(expression)
  endfunction()